Published: May 17, 2010

In an escalation of protest tactics, five immigrants dressed in caps and gowns held a sit-in on Monday at the Tucson offices of Senator John McCain, calling on him to sponsor legislation to open a path to legal status for young illegal immigrants.

Four of the protesters, including three who are in the country illegally, were arrested Monday evening on misdemeanor trespassing charges. The three were expected to face deportation proceedings.

It was the first time students have directly risked deportation in an effort to prompt Congress to take up a bill that would benefit illegal immigrant youths.

Separately on Monday, a lawsuit was filed in federal court in Phoenix by a coalition of civil rights, labor and religious groups challenging the new Arizona law that allows the police to detain suspected illegal immigrants as unconstitutional, saying it would lead to racial profiling.

Though it was the fifth suit challenging the law, it was widely believed to have the best chance of being heard by the courts given the groups’ experience and the nature of the complaint.

Brooke Buchanan, a spokeswoman for Mr. McCain, said of the protesters, "The individuals have a right to peacefully protest in the senator’s office,” and added that Mr. McCain "understands the students’ frustrations.”

But she said: "Elections have consequences, and they should focus their efforts on the president and the Democrats that control the agenda in Congress.”

Mr. McCain, a Republican, has in years past repeatedly sponsored a bill that would offer legalization for illegal immigrant students who were brought to the United States as children by their parents, known to its supporters as the Dream Act. But this year he has not. Mr. McCain is facing a primary challenge from J.D Hayworth, a talk show host who has taken a tough stand on illegal immigrants.

The students protesting in Mr. McCain’s office said they wanted to increase pressure on Congress to pass the Dream Act this year, even if lawmakers do not take up a broader overhaul of the immigration system. The student bill is currently part of a Democratic proposal for an overhaul, largely written by Senator Charles E. Schumer of New York.

"I’ve been organizing for years, and a lot of my friends have become frustrated and lost hope,” said one of the students, Lizbeth Mateo, 25. "We don’t have any more time to be waiting. I really believe this year we can make it happen.”

Ms. Mateo, who came to the United States when she was 14, said she paid full tuition to earn a degree from California State University, Northridge, the first member of her family to graduate from college. She said her plans to attend law school had failed because she lacked legal status.

Ms. Mateo was arrested, along with Mohammad Abdollahi, 24, of Ann Arbor, Mich.; and Yahaira Carrillo, 25, of Kansas City, Mo. All three are illegal immigrants.

Also arrested was Raúl Alcaraz, 27, an immigrant from Mexico who is a legal resident and a counselor at a Tucson high school.

The protesters walked into Mr. McCain’s office just before noon and sat in the lobby.

Tania Unzueta, 26, who is from Los Angeles, joined the sit-in, but she said the group decided she should leave the protest in order to avoid arrest.

Mr. Abdollahi said he could not return to Iran, where he was born, because he is gay and feared persecution there.

Margo Cowan, a lawyer representing the students, said that the Tucson police said they would advise federal immigration authorities of the arrests, and that she expected the students would be put in immigration detention.

Illegal immigrant students have become increasingly public in their protests in recent months, as the prospects for an immigration overhaul faded in Washington. Four immigrant students walked from Miami to Washington, arriving in late April. So far, immigration authorities have not moved to detain student protesters.

Lawmakers are divided over whether to take up the Dream Act as separate legislation. Andy Fisher, a spokesman for Senator Richard G. Lugar of Indiana, a Republican who is a lead sponsor of the bill, said that the senator did not support any effort to advance a comprehensive immigration overhaul this year, but that he believed the Dream Act could be "doable” separately.

An aide to Senator Richard J. Durbin of Illinois, a Democrat who is the act’s other lead sponsor, said he continued to see it as part of an overhaul.

Lawyers for the groups that filed the suit over the Arizona immigration law Monday took aim at a chief argument of its supporters: that it largely parallels existing federal statutes. The lawyers said the Arizona law went further because federal agents are not required to check the immigration status of people they stop or arrest, as the state law requires.